1. Field of the Invention
This invention relates to a guidance system for a missile or projectile, for example a terminally-guided mortar shell.
2. Discussion of the Prior Art
One proposed guidance system comprises a target sensor including a steerable dish antenna coupled via a transceiver to a series of range gates which discriminate components of the return signal reflected from points within a series of range bands and enters these components into respective appropriate ones of a series of range channels of the system. The antenna is steered to execute a scan pattern over a field of view of the sensor. It has been proposed for such a system to have a resolution sufficient, at least when the projectile gets near to a target, to be able to discriminate returns from different portions of the target. A target tracking sub-system can then use the return signals to derive reflector steering signals which maintain the reflector tracked, not merely onto the target, but rather onto some desired aim-point on the target. The target return, say from a tank, comprises a series of discrete components returned from respective reflective items or features distributed over the target, probably along with some ground clutter returns and spurious signals. There have been proposed various ways of processing in the return signals with a view to guiding the weapon onto the preferred aim point in the face of difficulties arising from the possibly uneven distribution of the reflective items on the target and the clutter and spurious signals. The object of this invention is to provide a guidance system incorporating an alternative form of signal processing which, in some situations, may be preferred.